Typo and re-organized methods
Typo and re-organized methods

Re-organized methods section to better differentiate methods that apply to the MarkerClusterGroup from methods applying on Clusters only.

nerik/Leaflet.markercluster,604557209/byzgf,Leaflet/Leaflet.markercluster,Leaflet/Leaflet.markercluster,frenomus/Leaflet.markercluster,nerik/Leaflet.markercluster,zverev/Leaflet.markercluster,ghybs/Leaflet.markercluster,frenomus/Leaflet.markercluster,zverev/Leaflet.markercluster,604557209/byzgf,ghybs/Leaflet.markercluster